Question

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Fishes of the family Polynemidae are called threadfins.
Reason R: Upper part of pectoral fins of polynemids modified into thread like filaments.

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

In ichthyology exams, pay close attention to directional terms like "Upper vs Lower" or "Dorsal vs Ventral".
For Polynemidae (Threadfins), the tactile filaments are always on the ventral/lower side of the pectoral fin base.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
This is an Assertion-Reason question regarding the morphological characteristics and common nomenclature of the family Polynemidae.
Detailed Explanation:

• Analysis of Assertion A: The family Polynemidae consists of marine and brackish water fishes commonly known as "threadfins". This name is derived from their unique pectoral fin structure. Thus, Assertion A is true.

• Analysis of Reason R: In polynemids, the pectoral fin is divided into two distinct sections. The lower (ventral) part of the pectoral fin consists of several free, filamentous rays that are highly elongated and resemble threads. These filaments serve as tactile sensory organs to detect prey in murky water.

• Correction for Reason R: The statement incorrectly claims the "Upper part" is modified. In reality, it is the lower part. The upper part of the pectoral fin is normal and used for swimming. Thus, Reason R is false.

• Conclusion: Since the assertion is a correct statement of fact and the reason contains a morphological error regarding the position of the filaments, option (C) is the correct choice.

Step 2: Final Answer:
Assertion A is true, but Reason R is false because the free thread-like filaments are part of the lower, not the upper, pectoral fin.